While light hinged doors, such as kitchen cupboard doors, which are not subject to forces which tend to open them unintentionally, may be held in closed position with such simple devices as springs, magnets or friction catches, doors which must resist unintentional opening as a consequence of relatively substantial forces require positive latches or locks. Such positive holding devices usually comprise a bolt mounted within a box or case enclosure at the edge of the door opposite the hinges with allowance for limited reciprocating movement so that the catch can emerge to engage fixed stop structure and be retracted to permit opening and closing of the door. Springs usually are provided to urge the bolt outwardly toward extended position, especially in a latch, a manually operable handle or lever being provided to retract the bolt when the door is to be opened. A latching device may or may not be provided with locking means.
Because it is desirable by means of the door latch to dependably hold the door closed without allowing movement while in the closed position that might cause annoying noise, it has been necessary to observe relatively close tolerances in mounting the cooperating latch and fixed stop. The catch must engage the stop and hold the door against the fixed structure to which it is hinged. Frequently, adjustments had to be made after the latching equipment has been mounted to correct a loose condition. The requirements of accuracy and possible necessity of changing the mounting resulted in increased labor costs in the achievement of quality construction.
The latch or lock of this invention permits much greater tolerance in the relative positions of the latching mechanism and the fixed stop when the parts are being installed so that less time and care is involved in mounting the equipment. After mounting has been completed, the position of the catch with respect to the fixed stop is easily adjustable by turning with a screwdriver a control post at the rear end of the latch bolt to alter the angle of emergence of the bolt from the case enclosure. A small hole is provided in the top of the bolt case to permit access to this adjusting post when the bolt is extended with the catch confronting the fixed stop. The post is turned until a light but sufficient pressure is achieved between the catch and the stop so that with the application of ordinary forces, the door is held against any movement.
Accordingly, the principle object of the invention is to provide a hinged door latch or lock having a bolt the angle of emergence of which may be adjusted over a limited range to adjust the position of the catch relative to the fixed stop surface to hold the door firmly in closed position.